Luminaires with automated and remotely controllable functionality are well known in the entertainment and architectural lighting markets. Such products are commonly used in theatres, television studios, concerts, theme parks, night clubs, and other venues. A typical product will commonly provide control over the pan and tilt functions of the luminaire allowing the operator to control the direction the luminaire is pointing and thus the position of the light beam on the stage or in the studio. Typically this position control is done via control of the luminaire's position in two orthogonal rotational axes usually referred to as pan and tilt. Many products provide control over other parameters such as the intensity, color, focus, beam size, beam shape, and beam pattern. The beam pattern is often provided by a stencil or slide called a gobo which may be a steel, aluminum, or etched glass pattern. The products manufactured by Robe Show Lighting such as the ColorSpot 700E are typical of the art.
The optical systems of such luminaires may include a beam shaping optical element through which the light is constrained to pass. A beam shaping element may comprise an asymmetric or lenticular lens or collection of lenses that constrain a light beam that is symmetrical and circular in cross section to one that is asymmetrical and predominantly elliptical or rectangular in cross section. A prior art automated luminaire may contain a plurality of such beam shapers each of which may have a greater or lesser effect on the light beam and that may be overlapped to produce a composite effect. For example, a weak beam shaper may constrain a circular beam that has a symmetrical beam angle of 20° in all directions into a primarily elliptical beam that has a major axis of 30° and a minor axis of 15°. A more powerful beam shaper may constrain a circular beam that has a symmetrical beam angle of 20° in all directions into a primarily elliptical beam that has a major axis of 40° and a minor axis of 10°. It is also common in prior art luminaires to provide the ability to rotate the beam shaper along the optical axis such that the resultant symmetrical elliptical beam may also be rotated. U.S. Pat. No. 5,665,305; U.S. Pat. No. 5,758,955; U.S. Pat. No. 5,980,066; and U.S. Pat. No. 6,048,080 disclose such a system where a plurality of discrete lens elements are used to control the shape of a light beam.
FIG. 1 illustrates a typical multiparameter automated luminaire system 10. These systems commonly include a plurality of multiparameter automated luminaires 12 which typically each contain on-board a light source (not shown), light modulation devices, electric motors coupled to mechanical drive systems, and control electronics (not shown). In addition to being connected to mains power either directly or through a power distribution system (not shown), each automated luminaire 12 is connected in series or in parallel to data link 14 to one or more control desks 15. The automated luminaire system 10 is typically controlled by an operator through the control desk 15.
FIG. 2 illustrates a typical automated luminaire 12. A lamp 21 contains a light source 22 which emits light. The light is reflected and controlled by reflector 20 through an aperture or imaging gate 24 and then through a variable aperture (not shown). The resultant light beam may be further constrained, shaped, colored, and filtered by optical devices 26 which may include dichroic color filters, beam shapers, gobos, rotating gobos, framing shutters, effects glass, and other optical devices well known in the art. The final output beam may be transmitted through output lenses 28 and 31 which may form a zoom lens system.
FIG. 3 and FIG. 4 illustrate the construction and operation of a prior art example of a beam shaper 30. FIG. 3 illustrates a beam shaper 30 that comprises a disc of optically transparent material such as glass or polycarbonate that is embossed or molded with a pattern or array of raised or lowered linear areas 32 to form an array of ribbed or lenticular lenses. When the substantially circular light beam passes through this ribbed or lenticular lens the cross section 34 of that beam will be constrained to a cross section that is asymmetrical and predominantly elliptical or rectangular in shape as shown in FIG. 4. Such a system may be rotated around an axis parallel with the optical axis of the luminaire to rotate the elliptical beam shown in FIG. 4, however, neither the size of the ellipse nor its eccentricity can be altered by this beam shaper 30. Prior arts systems may contain multiple such devices with different patterns such that the size and eccentricity of the effect can be selected by using the appropriate beam shaper 30. However, this selection is discrete and provides the user no opportunity to continuously, over a range, adjust the magnitude of the effect. For example, if a different degree of eccentricity is desired a different beam shaper 30 needs to be inserted into the light beam path. Assuming a luminaire had two beam shapers 30 that could be substituted for each other, three discrete degrees of eccentricity effect could be achieved: no beam shaper, beam shaper 1, and beam shaper 2. However, the user could not vary the degrees of eccentricity between these two effects. If two beam shapers 30 could simultaneously be placed in the beam then four (4) effects may be achieved: no beam shaper, both beam shapers simultaneously and, assuming the beam shapers were not the same, each would individually have a different degree of effect.
There is a need for an improved beam shaper mechanism for an automated luminaire which provides the ability to smoothly and continuously adjust the size and/or eccentricity of the constrained light beam over a range of sizes and/or degrees of eccentricity.